Browsing by Author "P, S.P."

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    Cryogenic machining induced corrosion resistance of magnesium alloy AZ91
    (Elsevier B.V., 2025) Marakini, V.; P, C.; P, S.P.; Achar, B.P.; Sahoo, B.; Bhat K, U.
    Magnesium (Mg) alloys are popular in the aerospace and automotive sector owing to their light-weight aspects. Amongst various Mg alloys, AZ91 alloy has been trending and needs to be completely explored. The corrosion resistance of AZ91 alloy has always been a question, hence needs further investigation. The impact of face milling operations under cryogenic conditions on the corrosion properties of AZ91 alloy is studied in the current work. Using electrochemical polarization testing technique with a 3.5 % NaCl solution, the optimal surface finish of the alloy produced by cryogenic assisted face milling has been contrasted with dry milling. The polarization method compares both specimens after testing them for 0.5 h. Cryogenic machining considerably minimized the roughness by upto 28 % with values ranging between 0.0525 µm and 0.1169 µm when compared to the 0.1259 µm and 0.0691 µm from dry condition. The comparatively low roughness surface from cryogenic condition demonstrated a relatively low corrosion rate (1.1992 mm/year in cryogenic; 1.2891 mm/year in dry), indicating that the corrosion rates are directly related to the surface roughness. The superior corrosion resistance of the cryogenic milled surface over the dry milled surface was supported by the polarization curves. Additionally, the elemental analysis test on the surfaces after the polarization test revealed that the cryogenic milled surface had less oxygen (44.28 wt% and 7.29 wt%) than the dry milled surface (47.13 wt% and 10.01 wt%), proving the superior corrosion resistance of cryogenic milled surface. © 2025 The Authors
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    Investigations on Open-Circuit Faults of Zigzag Autoconfigured Transformer-Based 12-Pulse Rectifier
    (Institute of Electrical and Electronics Engineers Inc., 2020) Kalpana, R.; P, S.P.; Vidyasagar, V.S.; Singh, B.
    High power industrial loads are often fed from front-end multipulse rectifier as its ability to effectively and inexpensively mitigate the harmonics on the input ac side, which is achieved by the multipulse autoconfigured transformer. This article analyzes and investigates the operability of the zigzag autoconfigured transformer-based 12-pulse rectifier under open-circuit faults at input ac terminals. Contrary to the prior art 12-pulse rectifiers, the availability of neutral point in zigzag autoconfigured transformer results in different modes of operation under open-circuit faults at input terminals. A detailed theoretical analysis is carried out to understand the operation of the zigzag autoconfigured transformer-based 12-pulse rectifier under open-circuit fault conditions. Further, the experimental results are presented from the laboratory prototype to validate the theoretical analysis. © 1972-2012 IEEE.
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    Meta-heuristic algorithm based optimization studies in cryogenic and conventional milling of magnesium alloy AZ91
    (Elsevier B.V., 2025) Marakini, V.; P, S.P.; D'Mello, G.; Bhat K, U.; Thakur, D.; Achar, B.P.
    The surface finish of a machined product is essential for assessing its quality and other attributes. Modeling the surface roughness and hardness of a machined component is challenging for several reasons. The present study examines the effectiveness of four meta-heuristic algorithms in optimizing surface characteristics like roughness (Ra) and hardness (HV) in the machining of magnesium alloy AZ91. Experiments with uncoated carbide inserts have been conducted under dry and cryogenic conditions. The study's input parameters are the depth of cut, feed rate, and cutting speed. Modeling and prediction studies have been conducted using Multi Layered Perceptron (MLP) Neural Network, and the output of this model has been considered as the objective function for the optimization algorithms. Algorithms, namely Particle Swarm Optimization (PSO), Bat Algorithm (BA), and recently developed algorithms, namely Jaya Algorithm (JAYA) and Fruit Fly Optimization Algorithm (FOA), have been tested. The optimization accuracy of FOA has been found to be superior to that of the other algorithms. As per the knowledge of the authors, this work probably presents a first attempt in applying the JAYA and FOA metaheuristic algorithms in the machining studies of an AZ series magnesium alloy. © 2025 The Authors